Web Inspector: Edit Breakpoint popover sometimes appears misplaced in top left

Web Inspector: Edit Breakpoint popover sometimes appears misplaced in top left
https://bugs.webkit.org/show_bug.cgi?id=120804

Patch by Joseph Pecoraro <pecoraro@apple.com> on 2013-09-05
Reviewed by Timothy Hatcher.

Grab the bounding rect immediately, instead of grabbing it from the element
after the user has selected the "Edit Breakpoint" context menu item. When
the popover was misplaced it was when using an element had been removed or
replaced in the DOM, and caused a bogus bounding client rect.

* UserInterface/Breakpoint.js:
(WebInspector.Breakpoint.prototype.editBreakpoint):
(WebInspector.Breakpoint.prototype._showEditBreakpointPopover):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@155165 268f45cc-cd09-0410-ab3c-d52691b4dbfc